A spin wave element is disclosed in a published US patent application 2007/0296516, and is provided with a ferromagnetic layer formed on a substrate, two or more input portions and a detecting portion. This spin wave element generates spin waves in the ferromagnetic layer with the same phase or different phase by passing a current into the input portions, and detects the propagating spin wave at the detecting portion.
In the spin wave element disclosed in the published US patent application, the spin wave propagates as a plane wave inside the ferromagnetic layer. However, if the spin wave propagates as a spherical wave, the spin wave will spread spherically to make it difficult to detect the spin wave at the detecting portion.